Liquid storage apparatus and image forming apparatus

Abstract

The liquid storage apparatus includes: a liquid storage chamber which is constituted by a flexible bag member and stores liquid; an exterior container which has walls constituted by a shape memory member and has a hermetically sealed space in which the liquid storage chamber is disposed, the shape memory member extending and contracting freely at temperatures not greater than a transformation temperature and recovering a memorized shape at temperatures not less than a shape recovery temperature; a forcing member which applies a contraction force to the walls of the exterior container in a direction in which the walls contract; and a temperature adjuster which adjusts a temperature of the shape memory member directly or indirectly so as to control a ratio of a portion of the shape memory member having temperatures not greater than the transformation temperature and deformed to a contracted shape by the contraction force of the forcing member and a ratio of a portion of the shape memory member having temperatures not less than the shape recovery temperature and recovering the memorized shape more extended than the contracted shape, so that a pressure in the liquid storage chamber is changed depending on a volume change of the exterior container due to deformation of the shape memory member.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a liquid storage apparatus for storing liquid, and to an image forming apparatus including this liquid storage apparatus.[0003]2. Description of the Related Art[0004]Various types of liquid storage apparatuses for storing ink to be supplied to an ink ejection head are known. An ink ejection head ejects ink supplied from the liquid storage apparatus toward an ejection receiving medium, such as paper, and forms images on the ejection receiving medium.[0005]Japanese Patent Application Publication No. 2004-230890 discloses an ink cartridge comprising: a housing which defines a first fluid tank; an air management system having an attachment to be supported by the housing; and an expansible bladder which defines a second fluid tank and which is supported by the attachment within the first fluid tank. The expansible bladder is configured to expand to thereby increase the second fluid tank from ...

AI Technical Summary

Benefits of technology

[0011]In this aspect of the invention, the portion of the shape memory member which has temperatures not greater than the transformation temperature and extends and contracts freely, is contracted due to the contraction force of the forcing member. In accordance with this contraction, the capacity of the external container is decreased and the capacity of the liquid storage chamber is also decreased. In this case, the pressure inside the liquid storage chamber is increased. On the other hand, the shape recovery portion of the shape memory member having temperatures not less than the shape recovery temperature extends and recovers the specific memorized shape. In accordance with this extension, the capacity of the external container is increased, and the capacity of the liquid storage chamber is also increased. In this case, the pressure inside the liquid storage chamber is decreased. By the temperature distribution adjustment by means of the temperature adjuster, it is possible to change the ratio of the portion of the shape memory member having temperatures not greater than the transformation temperature and contracted by the contraction force of the forcing member, and the ratio of the portion of the shape memory member having temperatures not less than the shape recovery temperature and recovering the memorized shape more extended than the shape at a temperature not greater than the transformation temperature. Consequently, even in the case of the liquid storage chamber having a large capacity, it is possible to create an appropriate pressure inside the liquid storage chamber and to thereby supply the liquid in a stable fashion.

[0028]According to the present invention, it is possible to adjust the pressure of the stored liquid or the height of the liquid surface appropriately, and hence liquid can be supplied in a stable fashion.

Problems solved by technology

On the other hand, in the case of an ink tank having a large capacity, since the force generated by the elastic deformation increases, then the negative pressure exceeds the appropriate limit and the ejection state of the ink ejection head is thus affected, leading to a decline in print quality.

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